Re: [PATCH V2] ublk: zoned: support REQ_OP_ZONE_RESET_ALL

[Ming Lei <ming.lei@redhat.com>]

On Thu, Aug 10, 2023 at 01:10:30PM +0000, Niklas Cassel wrote:
> On Thu, Aug 10, 2023 at 08:43:26PM +0800, Ming Lei wrote:
> > There isn't any reason to not support REQ_OP_ZONE_RESET_ALL given everything
> > is actually handled in userspace, not mention it is pretty easy to support
> > RESET_ALL.
> > 
> > So enable REQ_OP_ZONE_RESET_ALL and let userspace handle it.
> > 
> > Verified by 'tools/zbc_reset_zone -all /dev/ublkb0' in libzbc[1] with
> > libublk-rs based ublk-zoned target prototype[2], follows command line
> > for creating ublk-zoned:
> > 
> > 	cargo run --example zoned -- add -1 1024	# add $dev_id $DEV_SIZE
> > 
> > [1] https://github.com/westerndigitalcorporation/libzbc
> > [2] https://github.com/ming1/libublk-rs/tree/zoned.v2
> > 
> > Cc: Niklas Cassel <Niklas.Cassel@wdc.com>
> > Cc: Damien Le Moal <dlemoal@kernel.org>
> > Cc: Andreas Hindborg <a.hindborg@samsung.com>
> > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> > ---
> > V2:
> > 	- update comment as reported by Niklas
> > 
> >  drivers/block/ublk_drv.c      | 7 +++++--
> >  include/uapi/linux/ublk_cmd.h | 1 +
> >  2 files changed, 6 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> > index b60394fe7be6..3650ef209344 100644
> > --- a/drivers/block/ublk_drv.c
> > +++ b/drivers/block/ublk_drv.c
> > @@ -251,6 +251,7 @@ static int ublk_dev_param_zoned_apply(struct ublk_device *ub)
> >  	const struct ublk_param_zoned *p = &ub->params.zoned;
> >  
> >  	disk_set_zoned(ub->ub_disk, BLK_ZONED_HM);
> > +	blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, ub->ub_disk->queue);
> >  	blk_queue_required_elevator_features(ub->ub_disk->queue,
> >  					     ELEVATOR_F_ZBD_SEQ_WRITE);
> >  	disk_set_max_active_zones(ub->ub_disk, p->max_active_zones);
> > @@ -393,6 +394,9 @@ static blk_status_t ublk_setup_iod_zoned(struct ublk_queue *ubq,
> >  	case REQ_OP_ZONE_APPEND:
> >  		ublk_op = UBLK_IO_OP_ZONE_APPEND;
> >  		break;
> > +	case REQ_OP_ZONE_RESET_ALL:
> > +		ublk_op = UBLK_IO_OP_ZONE_RESET_ALL;
> > +		break;
> >  	case REQ_OP_DRV_IN:
> >  		ublk_op = pdu->operation;
> >  		switch (ublk_op) {
> > @@ -404,9 +408,8 @@ static blk_status_t ublk_setup_iod_zoned(struct ublk_queue *ubq,
> >  		default:
> >  			return BLK_STS_IOERR;
> >  		}
> > -	case REQ_OP_ZONE_RESET_ALL:
> >  	case REQ_OP_DRV_OUT:
> > -		/* We do not support reset_all and drv_out */
> > +		/* We do not support drv_out */
> >  		return BLK_STS_NOTSUPP;
> >  	default:
> >  		return BLK_STS_IOERR;
> > diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h
> > index 2685e53e4752..b9cfc5c96268 100644
> > --- a/include/uapi/linux/ublk_cmd.h
> > +++ b/include/uapi/linux/ublk_cmd.h
> > @@ -245,6 +245,7 @@ struct ublksrv_ctrl_dev_info {
> >  #define		UBLK_IO_OP_ZONE_CLOSE		11
> >  #define		UBLK_IO_OP_ZONE_FINISH		12
> >  #define		UBLK_IO_OP_ZONE_APPEND		13
> > +#define		UBLK_IO_OP_ZONE_RESET_ALL	14
> 
> For some reason, it seems like the UBLK_IO_OP_ZONE_* values
> are identical to the REQ_OP_ZONE_* values in enum req_op:

Yeah.

I think that is zoned interface abstraction, which should be
generic enough to use linux's definition for ublk's UAPI in 1:1.

The same mapping can be found in virtio-blk zoned spec.

> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/blk_types.h?h=v6.5-rc5#n371
> 
> I don't see any obvious advantage of keeping them the same,

Not sure I follow your idea, and can you share your exact suggestion?

UBLK_IO_OP_ZONE_* is part of ublk UAPI, but REQ_OP_ZONE_* is just kernel
internal definition which may be changed time by time, so we can't use
REQ_OP_ZONE_* directly.

Here you can think of UBLK_IO_OP_ZONE_* as interface between driver and
hardware, so UBLK_IO_OP_ZONE_* has to be defined independently.

> but if you want to keep this pattern, then perhaps you want
> to define UBLK_IO_OP_ZONE_RESET_ALL to 17.

Why do you think that 17 is better than 14?

I'd rather use 14 to fill the hole, meantime the two ZONE_RESET OPs
can be kept together.

Thanks,
Ming